A study was made of the male genitalia of five species which constitute the phyllosoma complex: Triatoma phyllosoma (Burmeister, 1835), T. pallidipennis (Stal, 1872), T. longipennis Usinger, 1939, T. picturata Usinger, 1939 and T. mazzottii Usinger, 1941; all of them were found naturally infected by Trypanosoma cruzi, and, except T. picturata colonizing human houses. These species are very similar, not only by the external aspects but also by their geographical occurence in Mexico. The structures which constitute these genitalias were analysed comparatively with the intention to increase the knowledge of the mentioned species, showing some morphological informations to the modern taxonomy. There were identified four aedeagus structures: phallosoma, struts, endosoma and vesica processes; one on articulatory apparatus, the gonopore process; and other on pygophore, the pygophore process. These structures show small variations in size and shape, emphasizing the relatioship between the species and the dificulty to the perfect understanding of the taxonomic status of each one.